JP2013506615A - Materials used as concrete additives - Google Patents

Abstract

The present invention relates to an admixture for a cement composition comprising microfibrillated cellulose and / or a dielectric thereof. The invention also relates to a method for producing the admixture and the use of microfibrillated cellulose and / or its dielectric in concrete admixture. The present invention further relates to a cement composition containing the admixture, a method for producing the same, and a use thereof.

Description

  The present invention relates to an admixture for a cement composition, wherein the admixture is a chemical that forms microfibrillated cellulose during use of the microfibrillated cellulose and / or its derivatives and / or admixtures. Instable cellulose pulp or cellulosic material modified to The present invention also relates to a method for producing the admixture. The present invention further relates to the use of microfibrillated cellulose and / or its derivatives in concrete admixtures. The invention further relates to the use of said admixture or unstable cellulose pulp or cellulose raw material in the production of cement compositions such as concrete, self compacting concrete, mortar, grout or pouring grout. The present invention relates to a cement composition or cement comprising the admixture, and a method thereof and a construction element made from the cement composition.

  Concrete is a construction material made from a mixture of cement, sand, stone and water. After concrete is placed in admixture with water, it solidifies and hardens by a chemical process known as a hydration reaction. Water reacts with the cement that binds the other ingredients together, eventually producing a stone-like material. Concrete is used to make scaffolds for roadways, buildings, ground, highways / roads, bridges / overpasses, parking lots, brick / block walls, and gates, fences and poles.

  An important area of interest in concrete technology is self-compacting concrete (SCC), which flows and fills itself by gravity. Thus, no external vibration or other compression is necessary. Hardened concrete will function as normal concrete in the structure. It is possible to produce very high performance concrete as self-compacting concrete. Since no compaction work is required, the noise level during construction is significantly reduced and one work stage is eliminated.

  The problem with SCC is material separation (or segregation) and the susceptibility of SCC to changes in feedstock. Due to the widespread problems of normal and low strength SCC, the use of SCC for concrete from low to normal strength will not be as wide as possible. Material separation usually brings undesirable properties to concrete. The material separation can be a separation of water or aggregate (or aggregate). In water separation, the water phase separates as the cement particles settle (or settle) over time. Aggregation separation occurs faster when the aggregate sinks in the paste phase. The paste is a mixture of water, cement, other fine powders and admixtures. Slight changes in raw material composition or moisture content can dramatically change the properties of SCC. This lack of robustness in performance is also an obstacle to the use of SCC.

  Therefore, there is a need for improved self-filling concrete materials. Furthermore, there is a need to improve thixotropy and particle suspension in the dry (or wet) state of standard concrete formulations.

  The infusion grout is intended to be used by a pressure grouting technique. What is required of these materials is inter alia high fluidity, low material separation and low bleeding. The poured grout requires very high fluidity. The strength requirements in every application are not so high. Therefore, the water-cement ratio is very high for many applications. This causes material separation problems and insufficient grout penetration.

  Several attempts have been made to solve the above-mentioned problems with thickeners such as water-soluble polysaccharides such as welan gum or cellulose derivatives. British Patent Publication No. 2 378 946 and International Publication No. WO 03/018505 disclose the preparation of admixtures for cement compositions, where polysaccharides and / or nanosilica are used as thickeners. U.S. Patent Publication No. 2003/159391 relates to a lightweight concrete mixture in which soluble cellulose derivatives are used as thickeners. For example, the use of welan gum as a stabilizing admixture is widely known in the concrete industry.

  Cellulose fibers have traditionally been used in concrete materials to improve the mechanical properties of the material: for example, US Patent Publications where cellulose fibers are used to improve the strength properties of dried samples. In 2005/112981. Also, for example, in a publication by Kuthcarlapati et al. (Metals Materials and Processes 20 (3): 307-314, 2008), cellulose nanowhiskers are being investigated as a reinforcing material for concrete. Furthermore, the main purpose of the publication mentioned above is to improve the mechanical properties of the dried sample, i.e. not to affect the undried formulation. Moreover, in the above-mentioned patent publications and publications, the amount of cellulose fiber used is large.

  The present invention represents a novel approach that solves the above-mentioned problems associated with material separation and bleeding of concrete blends. The present invention is based on the use of microfibrillated cellulose and / or its derivatives in a stabilizing admixture.

  The present invention relates to a cement admixture or admixture for a cement composition, wherein the admixture forms a microfibrillated cellulose during use of the microfibrillated cellulose and / or derivative thereof, and / or admixture. Modified unstable cellulose pulp or cellulose raw material, and optionally water.

  An important advantage of the present invention is that concrete water bleeding and aggregate settlement are reduced. The addition of microfibrillated cellulose and / or its derivatives increases the thixotropy of the paste both with and without the plasticizer. Water retention of microfibrillated cellulose and / or its derivatives is a valuable property when used as a concrete admixture. In the present invention, an admixture comprising microfibrillated cellulose is not used as a reinforcing additive.

  It is feasible to use microfibrillated cellulose as a stabilizing admixture, especially for concrete having a high water / cement (w / c) ratio, ie low to normal strength. Among other things, microfibrillated cellulose and / or its derivatives help to make self-compacting concrete more robust. Water bleeding and aggregate settlement are reduced, thus increasing the durability of the concrete. Water bleeding is effectively prevented by the finest fibril additive. Aggregate settlement is also dramatically reduced by microfibrillated cellulose. The use of admixtures containing microfibrillated cellulose and / or derivatives thereof also compensates for too few microparticles or poor quality of microparticles.

  In an environment with water, microfibrillated cellulose and / or its derivatives form self-assembled hydrogel networks, even at low concentrations. These gels of microfibrillated cellulose have high shear thinning and high thixotropy in nature. Due to the inherent properties of microfibrillated cellulose gel, this material also exhibits strong aggregate retention.

  It has not previously been shown that microfibrillated cellulose and / or its derivatives are used as thickeners or stabilizing admixtures in concrete applications.

The present invention also relates to a method for producing a cement admixture according to any one of the claims of the present invention, the method comprising:
Providing a microfibrillated cellulose and / or derivative thereof;
Mixing the microfibrillated cellulose and / or derivative thereof and, if necessary, water together;
-Optionally adding at least one plasticizer and / or dispersant to obtain said admixture before, during or after the step of preparing the microfibrillated cellulose;
including.

  The present invention relates to the use of microfibrillated cellulose and / or derivatives thereof in concrete admixtures. The present invention also relates to the use of microfibrillated cellulose and / or its derivatives or cement admixtures for controlling the rheology or material separation of the present invention.

  The invention also relates to the use of the admixture according to the invention in the manufacture of cement compositions such as concrete, self-compacting concrete, mortar, grout or pouring grout. The invention also relates to the use of unstable cellulose pulp and / or cellulose raw materials in concrete admixtures or in the manufacture of cement compositions such as concrete, self-compacting concrete, mortar, grout or pouring grout. Related.

  The present invention further relates to a cement composition comprising an admixture as defined in the present invention.

The present invention also provides
Mixing together the cement binder, the aggregate material, water and the admixture according to the invention as defined in the claims;
-Adding at least one plasticizer and / or dispersant, if necessary;
And a method for producing the cement composition.

  The invention further relates to a construction element made from the cement composition and a cement comprising the admixture according to the invention.

FIG. 1 shows optical microscope images of cellulose pulp (A), micronized cellulose pulp (B) and microfibrillated cellulose (C), and atomic force microscope images of microfibrillated cellulose (D). FIG. 2 shows the results of a rheological investigation of the paste mixture. The shear stress (Pa) versus shear rate (1 / sec) of a reference paste without plasticizer and microfibrillated cellulose, micronized pulp or a mixture containing pulp is shown. FIG. 3 shows the results of a rheological investigation of the paste mixture. The shear stress (Pa) vs. shear rate (1 / second) is shown for a reference paste without plasticizer and a mixture with and without microplasticizer containing microfibrillated cellulose. FIG. 4 shows the shear stress (Pa) vs. shear rate (1 / sec) for an unplasticized paste. The ratios of water (w / c) to cement of the reference, MFC-L2 0.25% and MFC-L2 0.125% are 0.400, 0.593 and 0.539, respectively. FIG. 5 shows the shear stress (Pa) vs. shear rate (1 / sec) of the plasticized paste. The ratio of water (w / c) to reference and MFC-L2 0.25% cement is 0.355 and 0.539, respectively. FIG. 6 shows after 15 shocks for a reference sample (A) and a concrete mixture comprising cellulose pulp (B), refined cellulose pulp (C) or microfibrillated cellulose (D). Shows the result of the spread obtained from the flow measurement (or flow measurement) at. FIG. 7 shows cross-sectional optical survey results showing material separation between a reference sample (A) and a concrete mixture containing cellulose pulp (B), refined cellulose pulp (C) or microfibrillated cellulose (D). Show. The height of each photograph is 2.75 mm. Material separation of 0mm-3mm, 3mm-6mm and about 20mm below the surface is shown. FIG. 8 shows by UV light the microstructure of a reference sample (A) and a concrete mixture containing cellulose pulp (B), refined cellulose pulp (C) or microfibrillated cellulose (D). Sectional optical survey results are shown. The height of each photograph is 2.75 mm. FIG. 9 shows water bleeding of a reference mixture having a w / c of 0.65 to 1.00 and a mixture having cellulose fibers (industrial MFC) and having a constant w / c of 1.00. 2 hours later). FIG. 10 shows Marsh viscosity values of a reference mixture having a w / c of 0.65 to 1.00 and a mixture having cellulose fibers (industrial MFC) and having a constant w / c of 1.00 ( Marsh viscosity value). FIG. 11 shows Marsh viscosity values and water for a reference mixture with a w / c of 0.65 to 1.00 and a mixture with cellulose (industrial MFC) and a constant w / c of 1.00. The bleeding value is shown. FIG. 12 shows water bleeding (after 2 hours) of a reference mixture having a w / c of 1.00 and a mixture having cellulose fibers (MFC-L1) and also having a w / c of 1.00. ). FIG. 13 shows Marsh viscosity values for a reference mixture having a w / c of 1.00 and a mixture having cellulose fibers (MFC-L1) and also having a w / c of 1.00. FIG. 14 shows Marsh viscosity values and water bleeding values for the reference mixture and the mixture with cellulose (MFC-L1). All the mixtures have w / c 1.00. FIG. 15 shows a reference mixture having a w / c of 1.00, a mixture comprising unstable cellulose pulp (Mix1, a precursor of MFC-L1) and also having a w / c of 1.00, and Desoi Figure 5 shows water bleeding (after 2 hours) with a mixture containing MFC-L1 (Mix2) fibrillated with AKM-70D1 and also w / c of 1.00. FIG. 16 shows a reference mixture having a w / c of 1.00, a mixture comprising unstable cellulose pulp (Mix1, a precursor of MFC-L1) and also having a w / c of 1.00, and Desoi The Marsh viscosity value of a mixture containing MFC-L1 (Mix2) fibrillated with AKM-70D and having a w / c of 1.00 is also shown.

  The present invention represents a novel approach to solving the problems related to material separation and bleeding of concrete blends. The present invention is based on the use of microfibrillated cellulose and / or its derivatives as a stabilizing admixture instead of using soluble polysaccharides. In an environment with water, the microfibrillated cellulose forms a continuous hydrogel network of dispersed microfibrils or bundles of microfibrils. This gel is formed by highly hydrated fibrils that are intertwined with each other, even at very low concentrations. The fibrils can also interact through hydrogen bonding. Its macrostructure is easily destroyed by mechanical stirring. That is, the gel begins to flow under high shear stress. It has not previously been shown that microfibrillated cellulose and / or its derivatives are used as thickeners or stabilizing admixtures in concrete applications.

  The present invention relates to cement admixtures, which are chemically modified and unstable which form microfibrillated cellulose during use of the microfibrillated cellulose and / or its derivatives and / or admixtures. Contains cellulose pulp or cellulose raw materials. The present invention also relates to a method for producing a cement admixture comprising microfibrillated cellulose and / or a derivative thereof, the method comprising the steps of preparing microfibrillated cellulose and / or a derivative thereof, and said microfibrillation At least one plasticizer and / or dispersant before, during or after the step of mixing together the cellulose and / or derivative thereof, and optionally water, and optionally preparing the microfibrillated cellulose To obtain the admixture. The invention further relates to the use of microfibrillated cellulose in concrete admixtures and to the use of the admixtures of the present invention in the manufacture of cement compositions such as concrete, self-filling concrete, mortar, grout or pouring grout. The invention further relates to the use of unstable cellulose pulp and / or cellulose raw materials in concrete admixtures or in the manufacture of cement compositions such as concrete, self-compacting concrete, mortar, grout or poured grout.

  The present invention further relates to a method for producing a cement composition, the method comprising mixing together a cementitious binder, an aggregate material, water and an admixture of the present invention. The present invention also relates to a cement composition comprising an admixture as defined in the present invention as well as a construction element made from said cement composition. The present invention further relates to a cement comprising the admixture according to the present invention.

  Unless otherwise specified, terms used in the specification and claims have meanings commonly used in the construction industry and in the pulp and paper industries. Specifically, the following terms have the meanings indicated below.

  The term "self-compacting concrete", also known as self-consolidating concrete or SCC, spreads in place without any mechanical vibrations, A highly fluid non-material separating concrete that fills the formwork and seals even the most dense rebar. This concrete is defined as a concrete mixture that can be placed purely by its own weight in the absence of vibrations.

  The term “cementitious binder” is a composite of calcium, aluminum, silicon, oxygen and / or sulfur with sufficient hydraulic activity to solidify or harden in the presence of water. All inorganic materials including things.

  The cements are common Portland cements, quick-set or super-set (or extra) sulfate-resistant cements, modified cements, alumina cements, high alumina cements, calcium alumina cements, and secondary Including, but not limited to, cement including ingredients (eg, fly ash, pozzolana and the like).

  The term “cementitious composition” refers to a material consisting of a cement binder and at least water. These materials are, for example, concrete, mortar and grout. In general, concrete consists of, for example, cement, water, aggregates and often admixtures.

  Instead of cement, other cement materials such as fly ash and slag cement can be used. Aggregates, generally fine and coarse aggregates, and chemical admixtures are added. Concrete aggregates include coarse aggregates such as gravel, limestone or granite, and fine aggregates containing sand. Ground stone or recycled ground concrete is also used as aggregate.

  The term “aggregate material” refers to a particulate material suitable for use in concrete. Aggregates may be natural or artificial, or recycled from materials previously used in construction. The term “coarse aggregate” means an aggregate having an upper limit size of 4 mm or more and a lower limit size of 2 mm or more. The term “fine aggregate” means an aggregate having an upper limit size of 4 mm or less.

  The term “cement / concrete admixture” refers to a material that is added in small quantities in relation to the mass of cement in the concrete mixing process to modify the properties of fresh concrete or hardened concrete. Say that.

  The term “cellulose raw material” refers to any cellulosic material that can be used to produce cellulose pulp, micronized pulp or microfibrillated cellulose. The raw material can be based on any plant raw material including cellulose. The feedstock can also be produced from a given bacterial fermentation process. The plant material may be wood. Wood can be softwood (coniferous) such as spruce, pine, fir, larch, Douglas fir (Bay pine) or American hemlock, birch, aspen, poplar, han tree, hardwood (hardwood) such as eucalyptus or acacia, or It can be a mixture of soft and hard wood. Non-woody materials can be agricultural waste, grass or cotton, corn, wheat, oats, rye, barley, rice, flax, cannabis, manila hemp, sisal hemp, jute, ramie, kenaf hemp, bagasse, bamboo or reed (reed) ) Other plant materials such as straw, leaves, bark, seeds, grains, flowers, vegetables or fruits. Cellulose raw materials could also be produced from cellulose-producing microorganisms. The microorganism is an Acetobacter genus (Acetobacter genus), Agrobacterium genus, Rhizobium genus, Pseudomonas genus or Alkaligenes genus, preferably Acetobacter genus, more preferably Acetobacter xylinum or Acetobacter Pasteuriana spp. possible.

  The term “cellulose pulp” refers to cellulose fiber, which can be any cellulose raw material by chemical pulping process, mechanical pulping process, thermomechanical pulping process or chemithermomechanical pulping process. Isolated (or isolated). In general, the fiber diameter varies between 15 μm and 25 μm and the length exceeds 500 μm, but the present invention is not intended to be limited to these parameters. An optical micrograph of a typical “cellulose pulp” is shown in FIG. 1A.

  The term “refined pulp” refers to refined cellulose pulp. Cellulose pulp by suitable equipment such as, for example, a refererer, grinder, homogenizer, colloid, friction grinder, fluidizing device (eg microfluidizer, macrofluidizer or fluidizer type homogenizer) or sonicator Is refined. In general, not all cellulose fibers are fully fibrillated. That is, there are still a large amount of cellulose fibers with dimensions that do not change, along with the refined cellulose material. The bulk fibers in the refined pulp can have a fibrillated surface. The finest part of the cellulose-based material in “refined pulp” consists of microfibrillated cellulose, ie cellulose microfibrils and bundles of microfibrils, with a diameter of less than 200 nm. An optical micrograph of a typical “refined cellulose” is shown in FIG. 1B.

  The term “microfibrillar cellulose” refers to an aggregate of isolated cellulose microfibrils or bundles of microfibrils produced from a cellulose source. Microfibrils generally have a high aspect ratio. The length may exceed 1 micron, while the number-average diameter is generally less than 200 nm. The diameter of the microfibril bundle may be larger, but is generally less than 1 μm. The finest microfibrils are similar to so-called elementary fibrils that are typically 2-12 nm in diameter. The size of the fibrils or fibril bundles depends on the raw materials and the method of disintegration (or disintegration). Microfibrillated cellulose may also include some hemicellulose. That is, the amount depends on the plant material. Cellulose raw material, by suitable equipment such as a referer inner, grinder, homogenizer, colloid, friction grinder, sonicator or fluidizer (eg microfluidizer, macrofluidizer or fluidizer type homogenizer), Mechanical defibration of microfibrillated cellulose from cellulose pulp or refined pulp is performed. “Microfibrillar cellulose” can also be isolated (separated) directly from a given fermentation process. The microorganism for producing cellulose according to the present invention comprises an Acetobacter genus (Acetobacter genus), Agrobacterium genus, Rhizobium genus, Pseudomonas genus or Alkaligenes genus, preferably Acetic acid bacteria genus, more preferably Acetobacter xylinum It may be a strain of Bacter pasturianas. “Microfibrillar cellulose” can also be any chemically or physically modified derivative of a bundle of cellulose microfibrils or microfibrils. Chemical modification can be based on, for example, carboxymethylation, oxidation, esterification or etherification reactions of cellulose molecules. Modification may also be achieved by physical adsorption of anionic, cationic or nonionic materials or any combination thereof on the cellulose surface. The described modifications can be carried out before, after or during the production of the microfibrillated cellulose.

  There are several synonyms that are widely used in microfibrillated cellulose. Examples: nanocellulose, nanofibrillated cellulose (NFC), nanofibril cellulose, cellulose nanofiber, nanoscale fibrillated cellulose, microfibrillated cellulose (MFC) or cellulose microfibril. In addition, microfibrillated cellulose produced by a given microorganism also has various synonyms. For example, bacterial cellulose, microbial cellulose (MC), biocellulose, Nata de Coco (NDC) or Cocodenata. The microfibrillated cellulose described in the present invention is not the same material as so-called cellulose whiskers, also known as cellulose nanowhiskers, cellulose nanocrystals, cellulose nanorods, rod-shaped cellulose microcrystals or cellulose nanowires. In some cases, similar terminology is used for both materials, for example by Kuthcarlapati et al. (Metals Materials and Processes 20 (3): 307-314, 2008), where the investigated materials are “cellulose nanofibers ( but they were clearly referring to cellulose nanowhiskers. In general, these materials do not have amorphous portions that provide a more rigid structure along the fibril structure, like microfibrillated cellulose. Cellulose whiskers are also shorter than microfibrillated cellulose, generally less than 1 micrometer in length.

  An optical micrograph of a typical “microfibrillar cellulose” is shown in FIG. 1C, where large cellulose fibers are no longer clearly visible. In FIG. 1D, due to the higher magnification, individual microfibrils and bundles of microfibrils can be seen having a diameter of less than 100 nm.

  The term “technical grade microfibrillar cellulose” or “technical MFC” refers to fractionated micronized pulp. This material is obtained by removing larger cellulose fibers from the refined cellulose pulp by a suitable fractionation technique such as filter cloth or membrane. Compared to “refined pulp”, “technical MFC” is visible in “cellulose pulp” or “refined pulp”. Generally, it does not contain large fibers with a diameter of 15 μm to 25 μm.

  The term “labile cellulose pulp or cellulose raw material” refers to a given modification of a cellulose raw material or cellulose pulp. For example, mediated oxidation of N-oxyl (eg, 2,2,6,6-tetramethyl-1-piperidine N-oxide) results in a highly unstable cellulosic material that is easy to fibrillate into microfibrillated cellulose. . International Publication No. WO09 / 084566 and Japanese Patent Publication No. 20070340371 disclose such modified examples.

  The term “microfibrillar cellulose L1” or “MFC-L1” refers to a microfibrillated cellulose material obtained from an unstable cellulose pulp. The destabilization is based on the oxidation of cellulose pulp, cellulose raw material or refined pulp. Due to destabilization, this cellulose pulp is easy to defibrate into microfibrillated cellulose. The destabilization reaction also provides aldehyde acid functionality and carboxylic acid functionality to the surface of the MFC-L1 fiber. International Publication No. WO09 / 084566 and Japanese Patent Publication No. 20070340371 disclose such modified examples.

  The term “microfibrillar cellulose L2” or “MFC-L2” refers to a microfibrillated cellulose material obtained from unstable cellulose pulp. Destabilization is based on carboxymethylation of cellulose pulp, cellulose raw material or refined pulp. Due to destabilization, this cellulose pulp is easy to defibrate into microfibrillated cellulose. The destabilization reaction also imparts carboxylic acid functional groups to the surface of the MFC-L2 fiber.

  The term “plasticizer” is a material that improves the fluidity of a cement paste and therefore improves the workability of concrete at a constant water / cement ratio, or a smaller amount while maintaining equivalent workability. It is a material from which concrete can be made with water.

  The term “dispersing agent” refers to a non-surfactant polymer or interface added to a suspension, usually a colloid, so as to improve the separability of the particles and prevent settlement or clumping. Says the activator.

  The term “concrete bleeding” refers to the formation of a layer of water on the concrete surface during the plastic phase of the concrete due to solid settlement.

  The term “internal bleeding” refers to the separation of water within the concrete structure itself.

  The term “injection grout” refers to a special grout intended to be used by a pressure grouting technique. What is required of these materials is inter alia high fluidity, low material separation and low bleeding.

  The present invention provides the following embodiments or any combination thereof.

  The present invention provides a cement admixture that is chemically modified to form microfibrillated cellulose during use of the microfibrillated cellulose and / or its derivatives and / or admixture. Contains a stable cellulose pulp or cellulosic material, and optionally water.

  The admixture may consist of, for example, a solid mixture or dispersion of microfibrillated cellulose and / or derivatives thereof.

  The admixture of the present invention may further comprise at least one plasticizer. Examples of plasticizers include polycarboxylic acid ethers or derivatives thereof.

  The admixture of the present invention may further comprise at least one dispersant. The admixture may further include one or more other ingredients such as antifoams, buffers, inhibitors, pH adjusters, biocides, preservatives, cure accelerators and / or air entrainers.

  The admixture of the present invention may comprise microfibrillated cellulose and the diameter of the cellulose microfibrils or bundles of microfibrils is less than 1 μm, preferably less than 200 nm, more preferably less than 100 nm.

  Microfibrillated cellulose can be a chemically or physically modified derivative of cellulose microfibrils or bundles of microfibrils. Microfibrillated cellulose can be obtained from raw materials including plant material or can be produced from a bacterial fermentation process. The plant material can be wood as described above.

  The admixtures of the present invention may include chemically modified unstable cellulose pulp or cellulose raw materials. Modification of cellulosic raw materials or cellulose pulp, such as N-oxyl mediated oxidation, results in highly unstable cellulosic materials that are easily defibrated to microfibrillated cellulose.

The present invention provides a method for producing a cement admixture comprising a mixture of microfibrillated cellulose and / or derivatives thereof, the method comprising:
Providing a microfibrillated cellulose and / or derivative thereof;
Mixing the microfibrillated cellulose and / or derivative thereof and, if necessary, water together;
-Optionally adding at least one plasticizer and / or dispersant to obtain said admixture before, during or after the step of preparing the microfibrillated cellulose;
including.

  The present invention provides for the use of microfibrillated cellulose and / or its derivatives in concrete admixtures. The present invention provides the use of microfibrillated cellulose and / or derivatives thereof, or an admixture according to the present invention to modify rheology or control material separation.

  The present invention provides the use of an admixture according to the present invention in the manufacture of cement compositions such as concrete, self-compacting concrete, mortar, grout or pouring grout. In a preferred embodiment of the present invention, the concrete is self-compacting concrete.

  The invention also includes the use of unstable cellulose pulp and / or cellulose raw materials in concrete admixtures or in the manufacture of cement compositions such as concrete, self-compacting concrete, mortar, grout or pouring grout. provide.

  In one embodiment of the present invention, the admixture further comprises a plasticizer and / or a dispersant. Microfibrillated cellulose or its derivatives may be used in combination with a plasticizer. The plasticizer may be added to the microfibrillated cellulose or its raw cellulose before, after or during the production of the microfibrillated cellulose.

  The present invention provides a cement composition comprising the admixture according to the present invention. The cement composition may further include a cement binder, an aggregate material, and water. The cement binder may be an inorganic material comprising calcium, aluminum, silicon, oxygen or sulfur compounds that has sufficient hydraulic activity to solidify or harden in the presence of water.

  In one embodiment of the present invention, the cement composition comprises an admixture and the amount of microfibrillated cellulose is 2% by weight or less of the cement binder, more preferably 0.2% by weight or less of the cement binder. The lower limit is 0.002% by weight of the cement binder, and the ratio of water to cement is 1.0 or less.

  In another embodiment of the present invention, the cement composition comprises an admixture, and the amount of microfibrillated cellulose is 2 wt% or less of water, preferably 0.2 wt% or less of water, The ratio of water to is 1.0 or more.

  In one embodiment of the invention, the composition further comprises at least one plasticizer and / or at least one dispersant.

  In one embodiment of the invention, the cement composition is concrete, preferably self-filling concrete. In another embodiment of the invention, the cement composition is an infused grout.

The present invention
Mixing together cement binder, aggregate material, water and admixture as defined in the present invention;
-Adding at least one plasticizer and / or dispersant, if necessary;
A method for producing a cement composition according to the present invention is provided.

  In one embodiment of the present invention, the method for producing a cement composition is characterized in that the amount of microfibrillated cellulose is 2% by weight or less of the cement binder, preferably 0.2% by weight or less of the cement binder, The lower limit is 0.002% by weight of the cement binder, and the ratio of water to cement is 1.0 or less.

  In another embodiment of the present invention, the method for producing a cement composition is characterized in that the amount of microfibrillated cellulose is 2 wt% or less of water, preferably 0.2 wt% or less of water, Including a ratio of 1.0 or more.

  The present invention provides a construction element made from the cement composition. The present invention provides a cement comprising the admixture according to the present invention.

  The present invention teaches a novel admixture for cement compositions comprising microfibrillated cellulose and / or derivatives thereof. A preferred embodiment of the present invention relates to the use of microfibrillated cellulose as a concrete admixture.

  The present invention is based on the use of microfibrillated cellulose and / or its derivatives as stabilizing admixtures for concrete. In an environment with water, the microfibrillated cellulose forms a continuous, hydrogel network of dispersed microfibrils or bundles of microfibrils. This gel is formed by highly hydrated fibrils that are intertwined with each other, even at very low concentrations. The fibrils can also interact through hydrogen bonding. Its macroscopic structure is easily destroyed by mechanical stirring. That is, the gel begins to flow under high shear stress.

  In certain embodiments of the present invention, the chemical composition of the material was the same and only the degree of fibrillation was changed. The average fiber size decreased with fibrillation.

  In an environment with water, cellulose pulp and micronized pulp formed a phase-separated fiber suspension that did not show any clear thixotropy, while microfibrillated cellulose was at low concentrations. Even form a self-assembled hydrogel network. These gels of microfibrillated cellulose have high shear flow and high thixotropy in nature. Due to the inherent properties of microfibrillated cellulose gel, this material also exhibits strong aggregate retention.

  Laboratory testing was performed with a high water-cement (w / c) grout. It can be shown that the material separation of the injected grout is reduced by the use of the present admixture. In these tests, high water-cement ratio grouts were tested to confirm this property. Also, rheological testing with a wider range of loadings and different cellulose derivatives was performed to identify the best materials and loadings for different applications.

  The following examples are provided to further illustrate the invention and are not intended to limit the scope of the claims. Based on this description, those skilled in the art will be able to improve the present invention in a number of ways.

Materials Cellulosic Materials The following cellulose materials were used in Examples 1 and 3: cellulose pulp (Sample 1), micronized pulp (Sample 2) and microfibrillated cellulose (Sample 3). Cellulose pulp (Sample 1) was a bleached birch pulp (or birch pulp) made by a conventional chemical pulping process. The refined pulp (Sample 2) was made from the same cellulose pulp as Sample 1 using a conventional Voice Sulzer referer inner (300 kWh / t). Microfibrillated cellulose (sample 3) was made from refined pulp (sample 2) using an industrial fluidizer.

  The size of the cellulose material used can be estimated from the microscopic image of FIG. In the cellulose pulp (FIG. 1A) and the refined pulp (FIG. 1B), the cellulose fibers can be clearly seen with a normal optical microscope. Usually, the diameter of large fibers varies between 15 μm and 25 μm and the length is over 500 μm (FIGS. 1A and 1B). Even in the refined pulp, there are finer cellulose fibrils or bundles of fibrils (FIG. 1B). In microfibrillated cellulose, large cellulose fibers are no longer visible (FIG. 1C). With higher magnification, referring to the AMF image of FIG. 1D, highly intertwined individual cellulose microfibrils and fibril bundles with a diameter of 10 nm to 100 nm can be found.

  The following cellulosic materials were used in Examples 2 and 4: industrial grade microfibrillated cellulose (industrial MFC), microfibrillated cellulose L1 (MFC-L1), destabilization was cellulose pulp, Cellulose raw material or micronized pulp and based on oxidation of microfibrillated cellulose L2 (MFC-L2), destabilization is based on carboxymethylation of cellulose pulp, cellulose raw material or micronized pulp .

Cement The cement used for the injection grout was CEM II / AM (S-LL) 42.5N (Finsementti, Finland).

Investigation method of rheology of paste mixture
Paste mixing was performed with a Hobart mortar mixer. The mixing time was 3 minutes (2 minutes slow + 1 minute fast). The pulp and cellulosic material was first manually mixed with water (and optionally a plasticizer) by a whisk.

Rheology The rheology of the paste mixture was investigated with a viscometer (Rheotest RN4). After mixing, the paste was introduced into a coaxial cylinder for measurement. The shear rate was changed and the shear stress was measured.

Test Setup The composition of the paste mixture is shown in Table 1.

  Immediately after mixing, the rheology of the paste mixture was investigated. It took about 15 minutes to complete the test.

Test results The test results are shown in FIGS.

  Based on the rheology test (FIG. 2), it can be concluded that microfibrillated cellulose fibers increase the yield value and thixotropy of the paste.

  Because the amount of microfibrillated cellulose is low in the refined pulp, the refined pulp functions a little like microfibrillated cellulose, but with only a slight improvement in yield value and thixotropy. I also found out.

  It has been found how microfibrillated cellulose fibers interact with polycarboxylate based plasticizers (FIG. 3). The plasticizer reduced the yield value of the paste as expected, but thixotropy was not compromised. This was the opposite of the typical reaction with some inorganic nanoparticles. That is, it has already been found that a small amount of plasticizer impairs thixotropy.

Investigation of rheology of paste mixture (sample: industrial MFC, MFC-L1 and MFC-L2)
Method Mixing Paste mixing was performed with a Hobart mortar mixer. The mixing time was 3 minutes (2 minutes slow + 1 minute fast). The pulp and cellulosic material were first mixed with water (and plasticizer as needed) manually with a whisk.

Rheology The rheology of the paste mixture was investigated with a viscometer (Rheotest RN4). After mixing, the paste was introduced into a coaxial cylinder for measurement. The shear rate was changed and the shear stress was measured.

Test Setup The composition of the paste mixture is shown in Table 2. The water / cement ratio of the prepared pastes was adjusted so that all pastes had the same workability. This corresponds to a yield value that is almost constant.

  Immediately after mixing, the rheology of the paste mixture was investigated. The test took 15 minutes to complete.

Test results The test results are shown in Table 2, FIG. 4 and FIG.

  With these MFC additives it was possible to make very high water / cement ratio pastes with the same workability and stability. In this example, workability suitable for the reference paste was achieved by using a higher cement content. The effect of increasing the yield value compared to Example 1 was also found.

Method of investigation of concrete mixtures containing cellulosic material as admixture Mixing of concrete was carried out according to European standard EN 196-1 (Cement test method-Part 1: Strength measurement). The pulp and cellulosic material were first mixed with water (and plasticizer as needed) manually with a whisk.

The workability of the rheological concrete (aggregate <8 mm) was measured with a Haegermann Flow table. Flow values (or flow, flow values, flow) [mm] were measured before and after 15 impacts according to the DIN 18550 standard.

Water bleeding Concrete water bleeding [vol. %] Was measured 1 hour and 3 hours after mixing. The fresh mixture was poured into a 0.5 liter bowel after mixing was complete. The test settings were adapted from standard SFS5290.

Strength investigation Concrete samples (40 mm x 40 mm x 160 mm) were cast for strength investigation. Compressive strength and bending strength [MPa] were measured [EN-196-1] after 1, 7 and 28 days. The compressive strength was calculated as an average value of 6 times, and the bending strength was calculated as an average value of 3 times.

Cross-sectional investigation Petrographic cross-sections were made for optical microscopy. The cross section was impregnated (or impregnate) with fluorescent epoxy. The final size of the cross section was 35 mm × 55 mm × 25 μm. Micrographs of the cross section were taken with a Leica Qwin image analyzer.

Test Setup A 1.5% microfibrillated cellulose dispersion was tested in a European standard EN 196-1 concrete formulation. The maximum aggregate size was less than 8 mm (“CEN Reference sand”). Conventional cellulose pulp and refined cellulose pulp were also used. A reference mixture without additives was also made. The dryness, flowability, rheology and water retention of the formulations were investigated and the flexural strength, compressive strength and microstructure of the cured samples were measured.

Information on the solid content and composition of the material in the concrete mixture is shown in Table 3.

Results When fresh concrete cellulosic material is first mixed with concrete and water by a whisk, it is impossible to obtain a uniform dispersion using cellulose pulp (1) and refined pulp (2). I found out. Based on visual assessment, the microfibrillated cellulose (3) was more uniformly dispersed than the cellulose pulp (1) and the refined cellulose pulp (2).

Concrete water bleeding was measured at 1 and 3 hours after mixing. The results of bleeding are shown in Table 4. Rheological results are also shown in Table 4 and in the measurement photograph of FIG.

    In the reference mixture without cellulose, there was a large amount of bleeding. The flow value (flow value) was high, 245 mm, and this mixture also separated the material in the flow test (FIG. 6A).

  There was slight bleeding (less than 1%) in the concrete mixture containing microfibrillated cellulose. The flow value was moderate, 140 mm (see also FIG. 6D).

  There was a slight bleeding (less than 1%) in the concrete mix containing the refined cellulose pulp. The flow value was moderate and was 150 mm (FIG. 6C). It can be seen that the amount of refined pulp added was three times greater than the amount of microfibrillated cellulose added (Table 4).

  There was a large amount of bleeding in the concrete mixture containing cellulose pulp. The flow value was high, 235 mm, and this mixture also material separated in the flow test (FIG. 6B).

The hardened concrete cross-section survey results (Figure 7) show that the reference concrete mixture (A) had a large amount of bleeding and a large amount of aggregate settlement. The water and paste separated on the concrete surface and the aggregate was at the bottom.

  In the concrete mixture containing microfibrillated cellulose, there was no aggregate settlement as can be seen from FIG. 7D.

  In the concrete mixture containing the refined cellulose pulp, there was no aggregate settlement as can be seen from FIG. 7C. Moreover, it turns out that the addition amount of the refined | pulverized pulp was 3 times more than the addition amount of microfibrillated cellulose (Table 4).

  In concrete mixtures containing cellulose pulp, there was a large amount of aggregate settlement. Water and paste separated on the concrete surface as can be seen from FIG. 7C.

  Since the amount of microfibrillated cellulose is less in the refined pulp, when microfibrillated cellulose is used in the concrete mixture, less of the cellulosic material compared to the use of the refined cellulose pulp It can be seen that an additional amount is required.

  The microstructure was also investigated by UV light. The cross-sectional optical survey results are shown in FIG. It can be seen that there was a large amount of internal bleeding in the reference sample that was clearly off-standard (FIG. 8A). Internal bleeding formed a channel network inside the concrete. There was also some internal bleeding in the concrete mixture containing cellulose pulp (FIG. 8B), while internal bleeding in the mixture containing micronized cellulose pulp (FIG. 8C) or microfibrillated cellulose (FIG. 8D). The microstructure was good and uniform. The internal bleeding and internal channel network reduced the tightness and durability of the concrete with respect to the reference sample and the concrete mixture containing cellulose pulp.

  Measurements of compressive strength and flexural strength showed that any combination of these tests had little effect on the strength of the cellulose.

Method of investigating water bleeding and viscosity of injected grout using technical grade microfibrillated cellulose and MFC-L1 Mixing of the injected grout was performed with a high speed mixer (Desoi AKM-70 D). The mixing of cement, water and cellulose was always performed at 5000 rpm. First, water was added, followed by cellulose over a short premix time (less than 5 seconds), followed by cement. The mixing time with cement was 2 minutes. In some cases, there was a premixing (or dispersion) of cellulose at 5000 rpm or 10,000 rpm for 2 minutes.

Test method for fresh injection grout: By injecting 1 (1) liter of grout into a graduated measuring glass (volume 1000 ml and diameter 60 mm) and measuring the bleed water amount up to 2 hours Water bleeding was measured.

  Marsh viscosity was measured according to [EN 14117] using a Marsh funnel.

Test Setup and Results The composition and test results for the reference infused grout mixture and the industrial grade microfibrillated cellulose (industrial MFC) mixture are shown in Table 5 and Figures 9-11.

  The composition of the injected grout mixture containing microfibrillated cellulose fibers (MFC-L1) obtained from unstable cellulose pulp is shown in Table 6 and Figures 12-14. For the three mixtures (mixtures 2, 3 and 4), there was a premixing (or dispersion) of the cellulose at 5000 rpm or 10,000 rpm for 2 minutes.

The mixtures shown in Table 6 were mixed and premixed with water only as follows:
Reference sample: 1st water + cement + mixing (5000 rpm, 2 minutes)
Mixture 1: Reference (w / c = 1.00)-Water and cement were mixed for 1 minute at 5000 rpm. Cellulose was added to the mixture and mixing was carried out at 5000 rpm for 2 minutes.
Mixture 2: 0.100% of the cement dry cellulose-cellulose and water were mixed for 2 minutes at 5000 rpm. Cement was added to the mixture and mixing was performed for 2 minutes at 5000 rpm.
Mixture 3: Cement 0.05% dry cellulose-cellulose and water were mixed for 2 minutes at 10,000 rpm. Cement was added to the mixture and mixing was performed at 5000 rpm for 2 minutes.
Mixture 4: Cement 0.05% dry cellulose-cellulose and water were mixed for 2 minutes at 5000 rpm. Cement was added to the mixture and mixing was performed for 2 minutes at 5000 rpm.

  Experimental results showed that the microfibrillated cellulose fibers reduced the water bleeding of the injected grout and increased the viscosity. The relative increase in Marsh viscosity was less than the relative decrease in bleeding. For example, when w / c is 1.00, 17% vs 50% at 0.263% (industrial MFC) of cement, for example, when w / c is 1.00 20% vs. 63% at 0.05% (MFC-L1).

  Water bleeding tests showed that microfibrillated cellulose fibers reduced w / c 1.00 grout water bleeding to lower w / c reference mixture levels. For example, in a mixture with a w / c of 1.00, 0.34% by weight of dry cement cellulose fiber (industrial MFC) has less water bleeding than a reference mixture with a w / c of 0.75. Obtained.

  Based on the Marsh viscosity test, it can be concluded that the microfibrillated cellulose fiber increased the w / c 1.00 grout viscosity to a lower w / c reference mixture level. The increase in Marsh viscosity depends on the amount of cellulose fiber added. When the amount added is not so large, the increase in viscosity is small.

Preparation of microfibrillated cellulose from unstable pulp during the preparation of grout Microfibrillated cellulose additives are not dried (or wet, using commonly used machinery in industry) It can be made from unstable cellulose pulp during the preparation of cement formulations. For example, high speed mixers such as Desoi AKM-70D are commonly used to make the injection grout uniform. This example shows how this type of mixer can be used to fibrillate unstable pulp into a highly effective additive.

Test set-up and results with chemically modified unstable cellulose pulp, i.e. the same pulp used to produce MFC-L1, with no pre-dispersion and with pre-dispersion The composition of the injected grout mixture and the test results are shown in Table 7, FIG. 15 and FIG. References that do not contain any cellulose pulp are also included.

  When predispersed, the content of dried material (dried unstable cellulose pulp) was 1% of water. Pre-dispersion was performed at 10,000 rpm with a high speed mixer (Desoi AKM-70D). The resulting pre-dispersed cellulose pulp with a dry material content of 1% was used to make the poured grout.

  Mixing of cement, water and cellulose (premixed or not premixed) was performed at 5000 rpm. First, water was added, followed by cellulose over a short premix time (less than 5 seconds), followed by cement. The mixing time with cement was 2 minutes.

  Experimental results have shown that pre-dispersed chemically modified unstable cellulose pulp reduces the bleeding of injected grout water and improves Marsh viscosity. Without predispersion, water bleeding did not decrease and Marsh viscosity did not increase.

  Water bleeding tests showed that a pre-dispersed chemically modified unstable cellulose pulp reduced w / c 1.00 grout water bleeding by 65%.

Based on the Marsh viscosity test, it can be concluded that predispersed chemically modified unstable cellulose pulp increases the viscosity of the grout at w / c 1.00 by 19%.

Claims (23)

A cement admixture,
Microfibrillated cellulose; and / or
Derivatives thereof; and / or
A chemically modified unstable cellulose pulp or cellulose raw material that forms microfibrillated cellulose during use of the admixture; and
Water as needed,
A cement admixture characterized by containing.   The admixture according to claim 1, wherein the admixture is a mixture, such as a solid mixture or dispersion, of microfibrillated cellulose and / or derivatives thereof.   The admixture according to claim 1 or 2, wherein the admixture further comprises at least one plasticizer and / or dispersant.   The admixture comprises microfibrillated cellulose, and the diameter of the cellulose microfibril or the bundle of cellulose microfibrils is smaller than 1 μm, preferably smaller than 200 nm, more preferably smaller than 100 nm. The admixture according to any one of claims 1 to 3.   The admixture according to any one of claims 1 to 4, wherein the microfibrillated cellulose is a chemically or physically modified derivative of cellulose microfibrils or bundles of cellulose microfibrils. .   The admixture according to any one of claims 1 to 5, wherein the microfibrillated cellulose is obtained from a raw material containing a plant raw material or produced from a bacterial fermentation process.   The admixture according to claim 1, wherein the unstable cellulose pulp or cellulose raw material is obtained by N-oxyl-mediated oxidation. A method for producing a cement admixture according to any one of claims 1 to 7,
Providing a microfibrillated cellulose and / or derivative thereof;
Mixing the microfibrillated cellulose and / or derivative thereof, and optionally water together,
Adding at least one plasticizer and / or dispersant to obtain said admixture before, during or after the step of preparing the microfibrillated cellulose;
A method for producing a cement admixture, comprising:   Use of microfibrillated cellulose and / or its derivatives in concrete admixtures.   Use of an admixture according to any one of claims 1 to 7 in the production of cement compositions such as concrete, self-compacting concrete, mortar, grout or pouring grout.   Use of the microfibrillated cellulose and / or derivatives or admixtures according to any one of claims 1 to 7 for modifying rheology or controlling material separation.   12. Use according to claim 10 or 11, characterized in that the admixture further comprises at least one plasticizer and / or dispersant added before or during the preparation of the cement composition.   Use of unstable cellulose pulp and / or cellulose raw materials in concrete admixtures or in the production of cement compositions such as concrete, self-compacting concrete, mortar, grout or pouring grout.   A cement composition comprising the admixture defined in any one of claims 1-7.   The amount of microfibrillated cellulose is 2% by weight or less of the cement binder, more preferably 0.2% by weight or less of the cement binder, and the lower limit is 0.002% by weight of the cement binder. The cement composition according to claim 14, wherein the ratio is 1.0 or less.   The amount of microfibrillated cellulose is 2 wt% or less of water, preferably 0.2 wt% or less of water, and the ratio of water to cement is 1.0 or more. The cement composition as described.   The cement composition according to any one of claims 14 to 16, wherein the composition further comprises at least one plasticizer and / or dispersant.   18. Cement composition according to any one of claims 14, 15 or 17, characterized in that the cement composition is concrete, preferably self-filling concrete. A step of integrally mixing a cement binder, an aggregate material, water, and the admixture defined in any one of claims 1 to 7;
Adding at least one plasticizer and / or dispersant, if necessary;
The method for producing a cement composition according to any one of claims 14 to 18, characterized by comprising:   20. The method of claim 19, wherein during the manufacture of the cement composition, the microfibrillated cellulose is obtained from a chemically modified unstable cellulose pulp or cellulose raw material.   The amount of microfibrillated cellulose is 2% by weight or less of the cement binder, preferably 0.2% by weight or less of the cement binder, and the lower limit is 0.002% by weight of the cement binder, The method according to claim 19 or 20, wherein the ratio is 1.0 or less.   The amount of microfibrillated cellulose in the admixture is 2% by weight or less of water, preferably 0.2% by weight or less of water, and the ratio of water to cement is 1.0 or more. The method according to claim 19 or 20.   A construction element made from the cement composition according to any one of claims 14-18.